Conversion of hydrocarbons



April 23, @46 w. s. BONNELL ET AL 29399093 CONVERSION OF' HYDROCRBONSFiled April e, 194s sively diminishes to a point where its employment.compounds with the catalyst. While these side reactions may be held ata minimum by careful separate processes ofalkylation and' isomeriza-Patented Apr. 23, 1946 I s PATEN 1', ortica CONVERSION OF HYDROCARBONSwilliam s. Barmen, oakinont, and william w. Weinrich, Fox ChapelBorough, Allegheny County, Pa., assignors to Gulf Research & De-

velopment Company, Pittsburgh, Pa., a corporav tion of DelawareApplication April c, 1943, serial No. 482,042 y 1,2 claims (ci.26o-essa) The present invention relates to the conversion ofhydrocarbons and is more particularly concerned withthe coordinatedoperation of alkylation and isomerlzation processes inthe production ofan alkylate.

In the manufacture of high antiknock fuels for internal combustionengines, much reliance has been placed upon the process of alkylationwherein isoparamns are reacted with one or more of the lower olens inthe presence of a suitable catalyst to produce a highlybranchedhydrocarbon havinganincreased number o f'carbon atoms;

Such processes have heretofore tilized refinery I and natural gases asthe principal source-of lower isoparafdns.

Frequently, however, thedemands l exceed the supply of availableisoparailins and it then becomes necessary and desirable to convert`normal paraillns, such as normal butane for exzation in each of theseprocesses, however, is an important factor since catalyst activityprogres- Ibecomes no longer economical. The underlying cause of catalystconsumption is not thoroughly understood but it appears that, whenaluminum chloride for instance is employed in hydrocarbon reactions,there areaccompanying side reactions which ultimately impair itsutility.4 According to one suggestion, the vigorous action of aluminum,chloride results in decomposition of the hydrocary bons to .supplyAproducts which form'additlon control of the process, it appearsimpossible orv impracticable to totally eliminate them. In all casesthere is a direct consumption of catalyst,

proportioned on the product produced and where tion are practiced thereis normally a total catalyst consumption equal to the combined require-A ments of these processes.

cnt invention to operate correlated alkylation and isomerizationlprocesses in such a manner that catalyst consumption is greatlyreduced.

Yet more particularly it has been discovered, in connection with thepresent invention, that catalysts of the Friedel-'Crafts type,'whichhave -been utilized to promote alkylation to a point where theircatalytic activity is completely or substantially exhausted for thispurpose, are still capable of catalyzing isomerization reactions.Accordingly, therefore, these catalytic materials, which are largely orsubstantially exhausted in' the alkylation reaction, may he withdrawnand introduced into the isomerization zone in order to isomerize normal`or slightly branched hydrocarbons under relatively good conditions ofcommerl I cial elllciency.

While the catalyst withdrawn from the alkylation zone yis not usuallyquite as active in promoting isomerizationas is fresh catayst,nevertheless when this step is followed by a limited subsequentisomer-,ization treatment in the presence l of fresh catalyst a materialsaving in over-.all

fresh catalystrequirement results. In short, initial isomerization inthe presence of the spent alkylation catalyst, followed by a limitedtreatment in thepresence of fresh catalyst, has been found to result insubstantially optimum conversion, fully as goed as where isomerizationis carried out entirely with fresh lcatalyst and at an increased rate ofconsumption.

From the foregoing it will be apparent that the present inventioncontemplates alkylation v and isomerization. in the presence of anyof'the conventional Friedel-Crafts catalysts in any of the forms in-which they are commercially known and employed. It is, however.more/advantageous to utilize the catalyst in fluid form in which itreadily separates from the reaction'product and is capable of beinghandled by pumps. To this end it is preferred, in large scaleoperations, to employ fluid catalyst sludges formed by 'the treatment ofaluminum chloride with higher boiling One such sludge has beendehydrocarbons. y scribed in the `copending United States applicationSerial No. 408.242,-1lled August 25, 1941. The products there disclosedare advantageously produced by the treatment of aluminum chloride withthe higher boiling hydrocarbons resulting from a sulfuric -acidalkylation process. Many equivalent materials. however, will, inYview-of the foregoing, suggest themselves to -those skilledl in theart.v

In orderI t6 afford a more complete under- It is an important objectachieved by the pres- Il standing of the present invention, reference lsent invention.

now made to the drawing. which comprises a flow sheet of a combinedalkylation and isomerization process embodying the principles of theDres- The apparatus therein represented comprises an absorber I suppliedwith isoparaflln through conduit I2 and pump i4. A lower conduit i6 andpump I8 supply suitable olens. such as ethylene, propylene, or butylene,to the lower portion of the absorber for dissolution within theisoparanln. While the 'isoparain and olefin employed may vary widely.asgwill be understood by those'skilled in the art, isobutane andethylene will be hereinafter selected for convenience in exemplication.More specically, it may be assumed that the conduit l2 handles ahydrocarbon product composed as largely as possible -of isobutane butcontaining a restricted proportion of the usual accompanyinghydrocarbons, such for example as normal butano. So also the olenintroduced in conduit i6 may comprise a hydrocarbon gas obtained fromthe cracking of Ahydrocarbon oils, and rich in the desiredoleiin.

In the absorber the liquid phase isobutane dissolves the olens to form ahomogeneous mixture which can be supplied by pump through conduits 22and 24 to an alkylation reactor 26.

The reactor is preferably constructed so as to insure violent agitationof its contents and may thus comprise a stirrer as indicated, althoughany other means for promoting intimate contact of the reactants issatisfactory. The catalyst, advantageously in the fluid form hereinabovementioned, is introduced through the conduits 28 and 30 with the aid ofa pump 32. Advantageously, the alkylation reactor 26 is suitablyconstructed to maintain a temperature between 0 andl 100 C., and anelevatedl pressure ample to assure liquid-phase operation. Theinvention, moreover, contemplates alkylation in thepresence of ahydrohalide such as hydrogen chloride where desired, and to this end asuitable inlet (not shown) may be provided for this promoter.

After residence withinthe reactor 2G for a suiiicient period of time toeffect optimum alhlation the product is conveyed through conduit i@ to asettling device 36 wherein the aluminum chloride sludge proceeds toseparate and settle to the bottom. Conduit 38 and pump 46 withdraw thesludge and pass a portion of the ow through branched conduit 42,controlled by valve 4d, back to the conduit v28 where it is admixed withthe incoming fresh catalystandthus recycled to the reactor 26. Theremaining portion of the ow through conduit 38, comprising the partiallyspent sludge, ilows to the isomerization zone. hereinafter described ingreater detail.

A portion of the eiiiuent from the settling chambei' 361s withdrawnthrough conduit 4i. valve 48 and conduit 50 into a stabilizer 52 wherethe isobutaxe and lighter gases are fractionated oil and removed throughconduit 54. The bottoms removed from the stabilizer at Si constitute analkylate of desired character.

' It is to be noted that in the foregoing' process a second portion ofthe eiliuent in the conduit d8 may be recycled to the reactor 26 throughconduits 58 and 24 and pump 20.

however. the isobutane charged to-the absorber through conduit 12usually contains a small proe portion of normal butano, it isadvantageous to continuously withdraw another portion of the recoveredisobutane in order to prevent an objectionable building .up of normalbutane inthe recycle system. ,This eiect is conveniently accomplished inthe present process by passing the re` mainder of the bottoms from thefractlonator 60 through valve I4 and conduit 16 to a fractionator 18operating to separate normal butane from the isobutane. The recoveredlsobutane together with that produced in the isomerization system isreturned through conduit 12 into the conduit B8. as will hereinafterappear in greater detail.

The remainder of the apparatus comprises an isomerization system havingan absorber il!) supplied with a normal paraihn, for example such asnormal butane, through inlet conduit 82 and pump 20' 84. Hydrogenchloride is introduced into the lower portion of the absorber throughconduit 88. The mixture formed in the absorber, comprising a solution ofhydrogenchloride in the liquid normal butane is conducted throughconduit 80, preheater 82 and conduit 94 to the isomerization reactor 96.It will be noted that the reactor is supplied primarily with catalystsludge from the settler 36 comprising spent catalyst from the alkylationsystem. The hydrocarbon mixture accordingly comes into contact with thespent catalyst suitably admixed with recycled catalyst withdrawn fromthe bottom of the reactor as at 98 and recirculated by means of pump |00through conp duit un.

The lsomerization reaction is preferably carried out in a liquid phaseat a temperature between 80 and 150 C. The reactor therefore is suitablyconstructed to maintain the desired temperature within this range. Itmay be advantageously supplied with a suitable inert solid liing such aspumlce, through which the hydrocarbon mixture is passed incountercurrent relation to the downcoming aluminum chloride sludge.

The partly isomerized hydrocarbon mixture and hydrogen chloride arewithdrawn from the reactor 96 throughV conduit ltd to a second stageisomerization reactor m6. This stage advantageously operates under theinfluence of fresh catalyst introduced through conduit |98 and pump H0in sufficient amount and under conditions of contact such as to resultin a high yield of isobutane. y

It is to be noted that the catalyst sludge accumulating in the bottom ofythe, reactor |08 is partly recycled through conduit l i2, the remain?'it combines with the partially spent alkylate The hydrocarbons passingoverhead from the Y stabilizer 62 are carried into a fractional-.or 6o,

A portion of the isobutane thus recovered is re cycled through valve B6,conduit 68 and a cooler 10 to the incoming butano conduit i2. Since.

catalyst introduced by way of conduit 3B.` In this way only a relativelysmall proportion oi' fresh catalyst is necessary to completeisomerization, a signiiicant proportion of the reaction being carriedout under the iniiuence of the residual y alkylate catalyst.

Operating in 'this manner the relatively restricted amount of catalystintroduced through HI8 passes throughthe reactor |08 after comhin-y ingwith the recycled catalyst sludgesupplled through I I2. The amount ofused catalyst passed through the conduit I I6. will in practice be equalto the amount of fresh catalyst added through conduit L08. Likewise, thespent catalystdis-` carded from the first stage isomerization'reactor86, as at 98, will be equivalent to the total amount derived from thealkylation process through contwo` stages of the isomerization reactionmay be critical material.

operated independently so'far as catalyst is conc'erned. Alternativelythe fresh catalyst may bel recycled in reactor |06 and discarded when ithas become fully or partially depleted in catalytic .activity as.desired. In such a process, the con- 'duit ||6 would be omitted and thefirst stage reactor would proceed to function under the ini'iuencesolely of the spent alkylation catalyst.- Various other modificationswill be apparent to those skilled in the art in view of the foregoing.In all modiiications, however.' the amount of catalyst required forisomerizaticn is less than would be' necessary in an equivalent processemploying fresh catalyst. The iinal yield is 'thus moreeconomicallyobtained with a substantial saving of The isomerized mixture containingthe hydrogen chloride promoter is withdrawn from the secondstage reactor|06 through conduit |20 to a fractionator |22 wherein the hydrogenchloride the alkylation process. Moreover, as hereinabovev is separatedand recycled to the absorber 80 to ethylene oi' 4.3.:1. VThe alkylationreactor 26 was voperated at"`a temperature of 130,F., and under anabsolute pressure of 364 pounds per square inch. Y

The catalyst introduced comprised an aluminum chloride sludge producedfrom aluminum chloride and the higher boiling hydrocarbons of thesulfuric acid alkylation process. and contained about 80 per cent AlClaand 20 per cent alkylate bottoms based on the total weight of thesludge. During the operations the weight balance on the alkylationreactor showed that 10.03

A equal to the 0.41 part by weightf'jof catalyst origthrough conduit|24, and the inlet line 86. The

fractionator bottoms pass by way of conduit |26 to a second fractionator|28 wherein propane and lighter gases are separated and pass oil as at|30. The bottoms from' this fractionator, comprising for exampleisobutane, normal butane and pentane, are conveyed through conduit |32into the fractionator la previously mentioned which functions toseparate the desired isoparains from the normal parailins and otherhydrocarbon impurities. Thus the isobutane passing overhead through line,12, and forming the desired product of the illustrative isomerizationprocess, is carried into the conduit 68 leading to the isoparafdn intake|2 of the alkylation process. The eiiluent accordingly supplies in partthe requirement of noted, the portion of the isobutane mixture withdrawnfrom the flnal fractionator 60 of the alkylation system through conduit16 passes into the iractionator 18 along with the isobutane mixture fromthe isomerization reactors. By virtue of this arrangement normal butaneis continuously removed from the recirculating alkylation system toprevent an objectionable percentage increase of this impurity in thefeed to the absorber |0.

The normal Ibutane and pentanes from the bottom of fractionator 18 areconveyed through conduit |34 into fractionator |36 which eliminates thepentanes at |30 and discharges normal butane from overhead through theconduit |40. Conduit |40 in turn recirculates the normal butane backtothe absorber 80 through the inlet linel! and pump 84.

The following speciilc examples are presented in order to illustrate thedetailed operation of the foregoing apparatus in accordance with theprinciples of the invention: l

. Example 1.-The absorber i0 was charged with ethylene and isobutanecontaining small amounts of paranlns as impurities. The mixture leavingthe bottom oi the absorber had a ratio of isobutane to ethylene of 3.4:1and a ratio of parailins 75 butane.

' Propane plus pentanes. 4.---..-

parts by weight of ethylene, 70.90 parts by weight of isobutane and18.66 parts by weight of other light hydrocarbons which were present asimpurities, were charged to the reactor along with 0.41 part by weightof the aluminum chloride sludge. Analysis of the eiliuent stream showedthat 26.66 parts by weight of alkylate having an A. S. T. M. octanenumber of over 90 was obtained, together with 0.20 part by weight ofethylene, 18.66 parts by weight of light paramns other than isobutane.and 54.07 parts by weight of isobutane suitable for recycling to theabsorber. spent catalyst withdrawn through conduit 38 was manyintroduced interne aikyiuon unit. The catalyst consumption in this stageamounted to one pound per eleven gallons` of alkylate produced atconduit 56. l

During this timea butane-HC1' mixture was prepared in the absorber l80and supplied to the rst stage isomerization reactor 96. This chargeconsisted of 0.89 parts by weight of isobutane, 19188 parts by weight ofnormal butane, and 0.37 part by weight of pentanes together with 1.75parts by weight of hydrogen chloride. The 0.41 part byweight of spentcatalyst from conduit-*38 was permitted to flow downwardly in thereactor through a packing of 2-mesh pumice, while thehydrocarbon-hydrogen chloride mixture was permitted to'pass upwardly incountercurrent rela tionship. The catalyst sludge was recycled. throughconduit |02 at a rate of 131 parts by weight per hour. In the meantime,0.41 part of completely consumed catalyst was withdrawn at 98. l Thereactor was so operated that the normall butane came in contact with thecatalyst for 151 minutes at a vliquid space velocity of 0.24, under aninternal pressure of 664 pounds persquare inch and'at a maintainedtemperature of 190 F. The eluent from the reactor 08 was made upasfollows:A

Parts by Weight Isobutane 3.43 Normal butane-;

v The eiiiuent was charged by way of conduit |04 of 0.27 under apressure and temperature the same as employed in the ilrst stagereactor.

The effluent from the reactor |06 was made up as follows: l

Parts by weight isobutane 8.46 Normal butane' -v. 11.87 Propane 0.23Pentanes 0.61 It accordingly contained v40 mol per cent of iso- Theamount of It is to be noted that in the previoiu example, the catalystfrom the second stage isomerization reactor was, after a short 4periodof recycling, withdrawn and discarded from the conduit Il. In short,conduit Il! was not employed and the two isomerization stages werepermitted to funcasas,

tion independently, the first under the influence of spent alkylatecatalyst and the second in the presence of fresh catalyst. As notedabove, however, some additional saving in catalyst consumption isafforded by returning the partly spent catalyst from reactor |06 throughconduit IIS to the first stage reactor.l In this way only a single pointof catalyst withdrawal is provided, at SB. thus assuring more completecatalyst utilization.

It is important to note that in an operation1 ment in the manufacture ofalkylate fuels fromparaiiins and isoparatlins normally available at therefinery. It will be appreciated from the foregoing that thehydrocarbons mentioned in the specific example are suggested only forpurposes of illustration and may be substituted by r equivalent olens,isoparaidns or normal paraiflns, as the case may be, capable of use inthe isomerization or aikylation process. It is to be understood that theinvention is not limited to the specic form of apparatus illustrated butmay be carried out in various equivalent forms of apparatus. Thetemperatures, pressures and other conditions moreover may be variedwidely within the ranges most suitable and advantageous for the desiredconversion effect. The process may be modiiied, where desired, tooperatesolely upon a feed of normal or relatively slightly branched paraflinsand a suitable olefin, in which case substantially the entire quantityof parafdns fed to the alkylation zone is derived from the isomerizationprocess.

What We claim is: y

1. The process for isomerizing parafn hydrocarbons, and for alkylatlngbranched paraiiln isomersfor theproduction of an' alkylate fuel, whichcomprises alkylating an isoparaflin with an olefin in the presence of aFriedel-Crafts catalyst, withdrawing the said catalyst when it hasbecome substantially incapable of eecting further alkylation,isomerizing a paraffin hydrocarbon at a temperature of the order of 80to 150 C. in the presence of the catalyst withdrawn from the alkylationzone, and subjecting the lastnamed product to further isomerization inthe presence of fresh Friedel-Crafts catalyst at a temperature of thesame order as that of the initial isomerization step..

a temperature of the order of 80 to 100 C. in the presence o thecatalyst wlthdrawn'from the alkylation zone, subjecting the last-namedproduct to further 'isomerization in the presence of fresh catalyst at atemperature of the same order as that of the initial isomerization stepand supplying the parafiln isomer from the isomerization process as afeed material to the alkylation zone. 3. The process for preparing analkylate which comprises alkylating an isoparailin Vwith an olefin inthe presence of .a Friedel-Crafts catalyst. withdrawing the-saidcatalyst when it has become substantially incapable o f effectingfurther alkylation, subjecting parailln hydrocarbons at a temperature ofthe order of 80 to 150 C. to a first stage isomerization in the presenceof the catalyst withdrawn from said alkylation zone, subjecting thehydrocarbon mixture from the first stage isomerization to a second stageisomerization in the presence of theretofore unused llriedel-Craitscatalyst at a temperature of they same order as that of the initialisomerization step and supplying isoparaiiins from-the second stageisomerization as a feed to the alkylation zone.

4. The process for preparing an alkylate fuel which comprises.alkylating an isoparamn with an olefin in the presence of aFriedel-Crafts catalyst, withdrawing the said catalyst when it hasbecome substantially incapable of effecting iurther alkylation,subjecting parafn hydrocarbons at a temperature of the order of 80 to150 C. to a first stage isomerization in the presence of the catalystwithdrawn from said alkylation zone, subjecting the hydrocarbon mixturefrom the first stage isomerization to a second stage isomerization inthe presence of less-spent Friedel-.Crafts catalyst at a temperature ofthe same order as that of the initial isomerization step and supplyingpartially expended catalyst from the second stage isomerization to saidfirst stage isomerization step and removing from said rst stageisomerization that catalyst which is incapable of effecting furtherisomerization.

5. The process for isomerizing paraffin hydrocarbons, and for alkylatingbranched paraflin isomers in the production of an alkyiate which vcomprises alkylating an isoparaiiin with an oleiin in the presence of analuminum halide catalyst, withdrawing the said catalyst, when it hasbecome substantially incapable of effecting further alkylation,isomerizing a paraiiln hydrocarbon at a temperature of the order oir 80to 150 C. in the 2. The process for isomerizing paraln hydro- A carbons,and for alkylating branched parailin isomers in the production of analkylate which comprises alkylating an isoparailin with an olefin in thepresence of a Friedel-Crafts catalyst,

withdrawing the said catalyst when it has become substantially incapableof effecting further presence of the catalyst withdrawn from thealkylation zone, and subjecting the last-named product to furtherisomerization in the presence of fresh aluminum halide catalyst at atemperature of the same order as that of the initial isomerization step.

6. The process for preparing an alkylate which comprises alkylatng anisoparamn with an oleiln in the presence of a catalyst comprising aliquid aluminum halide-hydrocarbon complex, withdrawing the saidcatalyst when it has be- .come substantially incapable of effectingfurther allg/lation, subjecting parafiin hydrocarbons to a ilrst stageisomerization at a temperature of the crder,of to 150 C. in the presenceof the catalyst withdrawn from said alkylation zone, subjecting thehydrocarbon mixture from the first stage isomerization to a second stageisomerization in the presence of fresh liquidaluminum-halide-hydrocarbon complex catalyst at a alkylation,isomeriziug aparailin hydrocarbon at'lrtemperature of the same order asthat ci' the initial is'omerization step'and supplying isoparailins fromthe second stage isomerization'as a lfeed to the alkylation zone.

7. The process for.producing a hydrocarbon aikylate which comprisesisomerizing normal paraftln hydrocarbons to isoparaiiins at a tempera,`ture of the order of 80 to 150 C. in the presence' the same order asthat ofthe initial isomerization step; `alkylating olefnic hydrocarbonswith the isoparafns in the presence of a Friedel and Crafts catalyst;removing catalyst from the alkylation step when it has becomesubstantially incapable of effecting further alkylation and using it asthe catalyst inthe first isomerization step.

8. The process for producing a hydrocarbon alkylate which comprisesisomerizing normal parailin hydrocarbons to isoparamns at a temperatureof the order of 80 to 150 C. in the presence of a Friedel and Craftscatalyst; subjecting the so-isomerized hydrocarbon and any accompanyingunisomerized hydrocarbons to further isomerization in the presence oftheretofore unused Friedel and Crafts catalyst at a temperature of thesame order as that of the initial isomerization step; alkylatingolei'lnic hydrocarbons with the isoparaflins in the presence of aFriedel and Crafts catalyst; removing catalyst from the alkylation stepwhen it has become substantially incapable of effecting furtheralkylation and removing partially spent catalyst from the secondisomerization step, and using these as the catalyst in the rstisomerization step.

9. The process for producing4 a hydrocarbon all-:ylatewhich comprisesisomerizing normal paraffin hydrocarbons to isoparaiiins at atemperature of the order of 80 to 150 C. in the presence of a fluidaluminum-halide-complex type cata\ lyst; subjecting the so-isomerizedhydrocarbon andfany accompanying unisomerized hydrocar-V bons to furtherisomerization` in thepresence of theretofore unused iiuidaluminum-halide-complex type catalyst at a temperature of the same orderas that of the initial isomerization step; alkylating oleiinichydrocarbons with the isoparaflins in the presence of a fluidaluminum-halidecomplex type catalyst; removing catalyst from thealkylation step when it has become substanan hydrocarbons toisoparaiiins at a temperalture of the order of 80 to 150 C. in thepresence of a iluid aluminum-halide-complex -type catalyst; subjectingthe so-isomerized hydrocarbon and any accompanying unisomerizedhydrocarbons to further isomerization in the presence of theretoforeunused uid aluminum-halide-complex type catalyst at a temperature of thesame order as that of the initial isomerization step; alkylatingoleflnic hydrocarbons with the isoparailins in the presence of a iluidaluminum-halidecomplex type catalyst; removing catalyst from thealkylation step when it has become substantially incapable of effectingfurther alkylation y and removing partially spent catalyst from thesecond isomerization step, and using these as the catalyst in the rstisomerization step.

1l. The process for producing a hydrocarbon alkylate which comprisesisomerizing normal parain hydrocarbons to isoparains at a'temperature ofthe order of 80 to 150 C. in a plurality of stages-in the presence of aFriedel and Crafts catalyst; conducting the successive isomerizati'on ifrom the alkylation step when it has become subtially incapable ofeiecting further alkylation and using it as the catalyst in the rstisomerization step.

l0. The process for producing a hydrocarbon alkylate which comprisesisomerizing normal parstantially incapable of effecting furtheralkylation and introducing this catalyst, into the isomerizationcatalyst at an isomerization stage prior tothe lastsuch stage.

12. The process for producing a hydrocarbon alkylate which comprisesisomerizing normal parafn hydrocarbons to isoparamns at a temperature ofthe order of to 150 C. in a plurality of stages in the presence of afluid aluminum-halide-complex type catalyst; conducting the successiveisomerization steps at temperatures of the same order; alkylating olenichydrocarbons with the said isoparaflins in the presence of a uidaluminum-hali'de-complex type catalyst; introducing fresh catalyst intothe last isomerization stage and into the alkylation step; circulatingcatalyst through successive isomerization stages from the lastisomerization stage to the rst isomverization stage, removing catalystfrom the alkyl

